1. Field of the Invention
This disclosure generally relates to geometrical instruments, and, more particularly, to terrestrial gravitation responsive levels and plumbs with work attaching means having elastic bias type clamping, or an encircling loop or strap.
2. Description of Related Art
In any type of construction, there are numerous components that must be precisely oriented. For example, wall studs must be vertical, floor joists must be horizontal, window frames must be square, and gravity drainage systems must be adequately graded. The basic tools for ensuring that such components are properly oriented are the level and the plumb.
The most common types of levels and plumbs are the bubble-type which use a sealed vial that is partially filled with a liquid. The resulting air bubble senses and indicates the orientation of the instrument based upon its position in the vial. When the vial is horizontal, the bubble will move to the center. When the vial is rotated, the bubble will move toward the higher end of the vial. Of course, levels and plumbs may also use a variety of other technologies, besides bubble vials, for sensing and indicating horizontal and/or vertical grades.
In practice, the bubble vial, or other level sensor, is mounted in a frame in order to facilitate its positioning on a test surface. The two most common types of frames are the box frame and the I-beam frame which are named after the appearance of their transverse cross-sections. The orientation of the vial in the frame depends on the intended use for the instrument. If the device is intended for use in measuring the horizontal orientation of a surface, then the vial is mounted parallel to the reference side of the frame and the tool is called a "level." On the other hand, when the vial is mounted perpendicular to the reference side of the frame, it can be used to measure the vertical orientation of a surface and is called a "plumb." In fact, most such instruments are provided with both horizontal and vertical bubble vials so that they can be used as both levels and plumbs. In some cases, the vial may even be mounted at an angle other than horizontal or vertical with respect to the reference side of the frame in order to check a particular grade or slope. Consequently, the term "level" is now used to broadly encompass geometrical instruments for sensing horizontal, vertical, and other angular orientations.
When "shooting a level" with a bubble-type level, the reference side or surface of the frame is placed flush against the surface of a test member to be measured. If the bubble is centered in the appropriate vial, then the surface is properly oriented and the member can be permanently secured. If the bubble is not centered in the vial, then the member must be rotated until the bubble moves to the appropriate position.
One drawback associated with such levels is that they usually require at least one hand for holding the level flush against the test member while it is being measured and/or positioned. Since it generally requires two hands to position and secure a large test member, a minimum of two people are needed in order to allow one person to hold the level while the other person holds the structural member. If the person holding the level is not diligent, then one end of the level may move away from the test surface so that the level produces a false reading. Similarly, if the other person cannot keep the test member sufficiently still, then an inaccurate reading will also be produced. Even with less unwieldy test members, it is generally not safe for a single person to hold the level in one hand and the structural member in the other since the slippage of either could result in damage to the instrument and/or injury to the user.
These issues have been addressed with conventional "prior art" technology by providing levels which can be independently secured to a test surface or member. For example, U.S. Pat. No. 4,970,796 discloses a self supporting spirit level tool with three types of fasteners--retractable nail-like pins for penetrating into the test surface, elastic cords for clasping the test member, and magnets for clinging to steel posts and pipes. Obviously, the pins will damage any surface into which they penetrate and the magnets will not cling to non-magnetic surfaces. Furthermore, the elastic cords are merely strung through holes in the body of the tool which can cause them to easily fray and/or slip out of position. Moreover, the cords are held on the tool in a position that can cause them to interfere with measurements being made while using the other fasteners.
U.S. Pat. No. 5,207,004 discloses a post level in which one end of a rubber band is knotted about an anchor and then wrapped around a post before the other end is hooked onto a peg extending from the level. Although this arrangement allows the rubber band to be easily replaced when broken or lost, frequent replacement of the rubber band can be necessary.
U.S. Pat. No. 5,421,094 discloses an adjustable level including a flexible cord connected to a return spring including a loop on the end of the cord for securing to a hook when the cord is wrapped around an object. Although this configuration provides an apparatus for storing the flexible cord when it is not being used, the cord cannot be wound manually and it can be difficult to slip the loop over the end of the hook. Furthermore, since the level uses only a single cord for support, it must be provided with an angled base in order to have adequate stability on curved surfaces.
U.S. Pat. No. 5,581,900 discloses a level clamp for temporarily attaching a level to a construction component. The clamp includes a pair of pivotally-mounted, spring-loaded opposed jaws for temporarily gripping the component. FIGS. 9-15 of that patent illustrate an embodiment in which the jaws are formed from a pair of bent-wire clips, each having a downwardly extending pair of legs with curved side segments and flattened bottom segments. However, as illustrated in FIG. 15 of this patent, the jaws merely pivot around a shaft and do not articulate or wrap around the component being measured. Consequently, the bottom segments of the jaws will be positioned flatly and securely against the side surfaces of a construction component only when the component has the general size and shape shown in FIG. 15.